#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

using mint = modint998244353;

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

int main() {
    ll N;
    cin >> N;
    vector<ll> A(N);
    vector<ll> B(N);
    vector<ll> C(N);
    for (ll i = 0; i < N; i++) {
        cin >> A[i];
    }
    for (ll i = 0; i < N; i++) {
        cin >> B[i];
    }
    for (ll i = 0; i < N; i++) {
        cin >> C[i];
    }

    ll INF = 1000000000000000023;
    ll ans = 0;

    // 0 -> 1 -> 0 -> 1 -> 0
    vector<vector<ll>> dp1(N + 1, vector<ll>(5, -INF));
    for (ll i = 0; i < 5; i++) {
        dp1[0][i] = 0;
    }
    for (ll i = 0; i < N; i++) {
        dp1[i + 1][0] = dp1[i][0] + A[i];
        dp1[i + 1][1] = max(dp1[i][0], dp1[i][1]) + B[i];
        dp1[i + 1][2] = max(dp1[i][1], dp1[i][2]) + A[i];
        dp1[i + 1][3] = max(dp1[i][2], dp1[i][3]) + B[i];
        dp1[i + 1][4] = max(dp1[i][3], dp1[i][4]) + A[i];
    }

    // 0 -> 1 -> 2 -> 1 -> 0
    vector<vector<ll>> dp2(N + 1, vector<ll>(5, -INF));
    for (ll i = 0; i < 5; i++) {
        dp2[0][i] = 0;
    }
    for (ll i = 0; i < N; i++) {
        dp2[i + 1][0] = dp2[i][0] + A[i];
        dp2[i + 1][1] = max(dp2[i][0], dp2[i][1]) + B[i];
        dp2[i + 1][2] = max(max(dp2[i][0], dp2[i][1]), dp2[i][2]) + C[i];
        dp2[i + 1][3] = max(dp2[i][2], dp2[i][3]) + B[i];
        dp2[i + 1][4] = max(max(dp2[i][2], dp2[i][3]), dp2[i][4]) + A[i];
    }

    for (ll i = 0; i < 5; i++) {
        ans = max(ans, dp1[N][i]);
        ans = max(ans, dp2[N][i]);
    }
    cout << ans << endl;
}